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<front>
<journal-meta>
<journal-id journal-id-type="publisher">EGUsphere</journal-id>
<journal-title-group>
<journal-title>EGUsphere</journal-title>
<abbrev-journal-title abbrev-type="publisher">EGUsphere</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">EGUsphere</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub"></issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/egusphere-2025-254</article-id>
<title-group>
<article-title>Saudi Rainfall (SaRa): Hourly 0.1&amp;deg; Gridded Rainfall (1979&amp;ndash;Present) for Saudi Arabia via Machine Learning Fusion of Satellite and Model Data</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Wang</surname>
<given-names>Xuetong</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Alharbi</surname>
<given-names>Raied S.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Baez-Villanueva</surname>
<given-names>Oscar M.</given-names>
<ext-link>https://orcid.org/0000-0002-2262-1698</ext-link>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Green</surname>
<given-names>Amy</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>McCabe</surname>
<given-names>Matthew F.</given-names>
<ext-link>https://orcid.org/0000-0002-1279-5272</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Wada</surname>
<given-names>Yoshihide</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Van Dijk</surname>
<given-names>Albert I. J. M.</given-names>
</name>
<xref ref-type="aff" rid="aff6">
<sup>6</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Abid</surname>
<given-names>Muhammad A.</given-names>
<ext-link>https://orcid.org/0000-0002-7389-7977</ext-link>
</name>
<xref ref-type="aff" rid="aff7">
<sup>7</sup>
</xref>
<xref ref-type="aff" rid="aff8">
<sup>8</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Beck</surname>
<given-names>Hylke</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff9">
<sup>9</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Department of Civil Engineering, College of Engineering, King Saud University, Riyadh, Saudi Arabia</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Hydro-Climate Extremes Lab (H-CEL), Ghent University, Ghent, Belgium</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>School of Engineering, Newcastle University, Newcastle upon Tyne, UK</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>Tyndall Centre for Climate Change Research, Newcastle University, Newcastle upon Tyne, UK</addr-line>
</aff>
<aff id="aff6">
<label>6</label>
<addr-line>Fenner School of Environment &amp; Society, Australian National University, Canberra, ACT, Australia</addr-line>
</aff>
<aff id="aff7">
<label>7</label>
<addr-line>Atmospheric, Oceanic and Planetary Physics (AOPP), Department of Physics, University of Oxford, UK</addr-line>
</aff>
<aff id="aff8">
<label>8</label>
<addr-line>National Centre for Atmospheric Science (NCAS), UK</addr-line>
</aff>
<aff id="aff9">
<label>9</label>
<addr-line>GloH2O LLC, Princeton, USA</addr-line>
</aff>
<pub-date pub-type="epub">
<day>03</day>
<month>02</month>
<year>2025</year>
</pub-date>
<volume>2025</volume>
<fpage>1</fpage>
<lpage>32</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2025 Xuetong Wang et al.</copyright-statement>
<copyright-year>2025</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/4.0/">https://creativecommons.org/licenses/by/4.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2025/egusphere-2025-254/">This article is available from https://egusphere.copernicus.org/preprints/2025/egusphere-2025-254/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2025/egusphere-2025-254/egusphere-2025-254.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2025/egusphere-2025-254/egusphere-2025-254.pdf</self-uri>
<abstract>
<p>We introduce Saudi Rainfall (SaRa), a gridded historical and near real-time precipitation (&lt;em&gt;P&lt;/em&gt;) product specifically designed for the Arabian Peninsula, one of the most arid, water-stressed, and data-sparse regions on Earth. The product has an hourly 0.1&amp;deg; resolution spanning from 1979 to the present and is continuously updated with a latency of less than two hours. The algorithm underpinning the product involves 18 machine learning model stacks trained for different combinations of satellite and (re)analysis &lt;em&gt;P&lt;/em&gt; products along with several static predictors. As a training target, hourly and daily &lt;em&gt;P&lt;/em&gt; observations from gauges in Saudi Arabia (&lt;em&gt;n&lt;/em&gt;=113) and globally (&lt;em&gt;n&lt;/em&gt;=14,256) are used. To evaluate the performance of SaRa, we carried out the most comprehensive evaluation of gridded &lt;em&gt;P &lt;/em&gt;products in the region to date, using observations from independent gauges (excluded from training) in Saudi Arabia as a reference (&lt;em&gt;n&lt;/em&gt;=119). Among the 20 evaluated &lt;em&gt;P&lt;/em&gt; products, our new product, SaRa, consistently ranked first across all evaluation metrics, including the Kling-Gupta Efficiency (KGE), correlation, bias, peak bias, wet days bias, and critical success index. Notably, SaRa achieved a median KGE &amp;mdash; a summary statistic combining correlation, bias, and variability &amp;mdash; of 0.36, while widely used non-gauge-based products such as CHIRP, ERA5, GSMaP V8, and IMERG-L V07 achieved values of -0.07, 0.21, -0.13, and -0.39, respectively. SaRa also outperformed four gauge-based products such as CHIRPS V2, CPC Unified, IMERG-F V07, and MSWEP V2.8 which had median KGE values of 0.17, -0.03, 0.29, and 0.20, respectively. Our new &lt;em&gt;P&lt;/em&gt; product &amp;mdash; available at www.gloh2o.org/sara &amp;mdash; addresses a crucial need in the Arabian Peninsula, providing a robust and reliable dataset to support hydrological modeling, water resource assessments, flood management, and climate research.</p>
</abstract>
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